U.S. patent number 7,584,531 [Application Number 11/873,302] was granted by the patent office on 2009-09-08 for method of manufacturing a golf club head with a variable thickness face.
This patent grant is currently assigned to Karsten Manufacturing Corporation. Invention is credited to Bradley D. Schweigert, John A. Solheim.
United States Patent |
7,584,531 |
Schweigert , et al. |
September 8, 2009 |
Method of manufacturing a golf club head with a variable thickness
face
Abstract
A method of manufacturing a golf club head with a variable
thickness face having a central thickened region surrounded by a
transition region tapering from the central thickened region to a
thinner peripheral region. The method includes locating a ball end
mill revolving about an axis generally normal to the inner surface
of the face plate at an initial location on a circumferential
intersection between the outer edge of the central thickened region
and a transition region. The inner surface of the face plate is
machined by moving the revolving ball end mill in a radial
direction outwardly toward and through the transition region and
the peripheral region to machine the inner surface of the face
plate creating a tool channel having a width as the ball end mill
traverses the transition region and thereby vary the thickness of
the face plate in the tool path. The ball end mill is then raised
in a direction normal to the surface of the face plate and
relocated to a subsequent location on the circumferential
intersection adjacent to the previous tool channel. The steps of
machining, raising and relocating the ball end mill are repeated
until the end mill has traversed the entire circumference of the
circumferential intersection. In preferred embodiments, the
machining step may vary the thickness of the transition region
along a variable path, which may be a straight line, a curved line,
or any other suitable path.
Inventors: |
Schweigert; Bradley D. (Anthem,
AZ), Solheim; John A. (Phoenix, AZ) |
Assignee: |
Karsten Manufacturing
Corporation (Phoenix, AZ)
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Family
ID: |
36998513 |
Appl.
No.: |
11/873,302 |
Filed: |
October 16, 2007 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20080039227 A1 |
Feb 14, 2008 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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11194958 |
Aug 1, 2005 |
7338388 |
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Current U.S.
Class: |
29/557 |
Current CPC
Class: |
A63B
53/0466 (20130101); A63B 60/00 (20151001); B23C
3/16 (20130101); B23C 5/1009 (20130101); A63B
53/0462 (20200801); A63B 53/0408 (20200801); A63B
53/0458 (20200801); B23C 2220/48 (20130101); Y10T
29/4998 (20150115); A63B 53/0416 (20200801); Y10T
29/49995 (20150115); A63B 53/042 (20200801) |
Current International
Class: |
B23P
13/04 (20060101) |
Field of
Search: |
;29/527.1,557
;473/329,345,349,346,342 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
"Cutting Tool Selection Impacts the Outcome of Hard Metal
Machining" by Mike MacArthur, Nov. 2003, viewed online Nov. 23,
2006(http://www.moldmakingtechnology.com). cited by other.
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Primary Examiner: Hong; John C
Parent Case Text
This is a division of application Ser. No. 11/194,958 filed Aug. 1,
2005, now U.S. Pat. No. 7,338,388.
Claims
What is claimed is:
1. A method of manufacturing a golf club head with a variable
thickness face plate, the variable thickness face plate including a
central thickened region surrounded by a transition region tapering
from the central thickened region to a thinner peripheral region,
the variable thickness face plate further including a first
circumferential intersection between the central thickened region
and the transition region and a second circumferential intersection
between the transition region and the thinner peripheral region,
the method comprising: providing a face plate having an outer
surface, an inner surface, and a first thickness; locating a ball
end mill revolving about an axis generally normal to the inner
surface of the face plate at an initial location on the first
circumferential intersection; machining the inner surface of the
face plate by moving the revolving ball end mill in a radial
direction outwardly toward and through the transition region and
the peripheral region to machine the inner surface of the face
plate creating a tool channel having a width as the ball end mill
traverses the transition region and the peripheral region and
thereby vary the thickness of the face plate in the tool channel;
raising the revolving ball end mill in a direction normal to the
surface of the face plate; relocating the revolving ball end mill
to a subsequent location on the first circumferential intersection
adjacent to the previous tool channel; and repeating the machining,
raising and relocating steps until the end mill has traversed the
entire circumference of the first circumferential intersection.
2. The method of claim 1, wherein the machining step varies the
thickness of the transition region from the first thickness to a
second thickness.
3. The method of claim 2, wherein the machining step forms the
peripheral region having constant thickness equivalent to the
second thickness.
4. The method of claim 1, wherein the step of machining further
comprises moving the revolving ball end mill along a straight line
outwardly toward and through the transition region and the
peripheral region.
5. The method of claim 1, wherein the step of machining further
comprises moving the revolving ball end mill along a curved line
outwardly toward and through the transition region and the
peripheral region.
6. The method of claim 1, wherein the first circumferential
intersection has a first aspect ratio and the second
circumferential intersection has a second aspect ratio, the second
aspect ratio being lower in value than the first aspect ratio.
7. The method of claim 1, wherein the first circumferential
intersection has a major axis of between 0.65 and 1.05 inches and
an aspect ratio of between 1.4 and 4.2.
8. The method of claim 1, further comprising providing a shell with
an opening and attaching the face plate to the opening in the shell
to form a hollow body golf club head.
9. The method of claim 8, wherein the shell is formed of
titanium.
10. The method of claim 1, wherein said ball end mill has a lower
cutting surface.
11. The method of claim 10, wherein the lower cutting surface of
the ball end mill does not cross into the central thickened region
during said machining step.
12. The method of claim 1 wherein the thinner peripheral region is
formed by removing at least 20% of said first thickness.
13. The method of claim 1, wherein the thinner peripheral region is
formed by machining at least 50% of said inner surface of said face
plate.
14. The method of claim 1, wherein the machining step is performed
such that no material is removed from the central thickened region
whereby the central thickened region remains at the first
thickness.
15. The method of claim 1, wherein the face plate is formed of
titanium.
16. The method of claim 1, wherein the central thickened region is
elliptical in shape.
17. The method of claim 16, wherein the transition region is
elliptical in shape.
18. The method of claim 16, wherein the central thickened region
has a major axis from 0.65 to 1.05 inches in length and a minor
axis from 0.25 to 0.45 inches in length.
19. The method of claim 18, wherein the central thickened region
has an aspect ratio between 1.4 and 4.2.
20. The method of claim 19, wherein: the major axis of the central
thickened region is approximately 0.85 inches; the minor axis of
the central thickened region is approximately 0.35 inches; and the
aspect ratio of the central thickened region is approximately
2.4.
21. The method of claim 20, wherein: the major axis of the
transition region is approximately 1.71 inches in length; the minor
axis of the transition region is approximately 1.21 inches in
length; and the aspect ratio of the transition region is
approximately 1.4.
Description
BACKGROUND OF THE INVENTION
This invention relates generally to golf equipment and, in
particular, to a golf club head with a variable thickness face and
a method of manufacturing the same.
Recent developments in golf club design have included improvements
in drivers, which are clubs used primarily to strike a golf ball
resting on a golf tee. These improvements have resulted in drivers
with club heads consisting of a hollow shell usually made of metal,
such as steel, aluminum, or titanium. These hollow shells have
relatively thin walls including a thin front wall that is used to
impact the golf ball. In order to prevent the front wall of these
hollow shells from permanently deforming or cracking upon ball
impact, it has become necessary to reinforce the front wall. One
example of a golf club head consisting of a hollow metal shell with
a reinforced front wall is disclosed in U.S. Pat. No. 4,511,145 to
Schmidt. The club head disclosed in the Schmidt patent has an
arched ridge extending between the heel and toe ends of the front
wall. The arched ridge design of the Schmidt provides adequate
reinforcement for drivers of moderate head volume, however, in an
effort to obtain better and better performance from these hollow
metal wood drivers, golf club manufacturers have increased the head
volume from the moderate volume of 200 cc's to over 400 cc's during
the past decade. As head size increases, less and less material is
available to reinforce the front wall of the club face within
acceptable weight limitations (i.e., around 200 grams mass).
Consequently, more exotic materials such as forged or cold rolled
titanium faces welded to a cast titanium body have been utilized in
these super-oversized drivers. The rear surfaces of the front walls
of these super-oversized drivers must be carefully contoured to
provide adequate structural strength with a minimum amount of
material.
The most critical region to reinforce the ideal ball impact point
of the front wall. Because most golfers' swings vary somewhat from
impact to impact, the reinforced region of the front wall must be
distributed around the ideal impact point. However, since
variations in a golfer's swing tend to be more in the heel and toe
direction, rather than up or down, the distribution of hits tends
to be within a horizontal, elliptical region rather than a circular
region centered around the center of the club face. Accordingly, an
elliptical, rather than a purely circular, reinforcement is
preferable. One example of a golf club head having a face with a
contoured rear surface is U.S. Pat. No. 6,354,962 to Galloway, et
al. The club head disclosed in Galloway has a face plate reinforced
with elliptical regions that are formed as part of the forging
process of the face plate. For clubs in which the club face is
machined from a wrought alloy sheet or other sheet material,
forming an elliptical reinforced region presents special problems.
The face cannot be machined properly on a lathe because the lathe
will produce only a circular reinforced region. In addition,
removing portions of the club face using a cutter in an elliptical
pattern may result in a face that is prone to fatigue cracks.
SUMMARY OF THE INVENTION
According to a first aspect of the present invention, a golf club
head is manufactured by removing a portion of the inner surface of
a face plate to form a central thickened region surrounded by a
transition region that tapers to a thinner peripheral region.
According to the illustrative embodiment, the face plate is a
rolled sheet titanium alloy between 0.130 and 0.180 inches thick
with a portion of the face plate being machined away to form the
transition region and the thinner peripheral region.
The method for manufacturing a golf club face plate includes
locating a ball end mill revolving about an axis generally normal
to the inner surface of the face plate at an initial location on a
first circumferential intersection between the outer edge of the
central thickened region and the transition region. The inner
surface of the face plate is machined by moving the revolving ball
end mill in a radial direction outwardly toward and through the
transition region and the peripheral region to machine the inner
surface of the face plate creating a tool channel having a width as
the ball end mill traverses the transition region and the
peripheral region and thereby vary the thickness of the face insert
in the tool channel. The ball end mill is then raised in a
direction normal to the surface of the face plate and relocated to
a subsequent location on the first circumferential intersection
adjacent to the previous tool channel. The steps of machining,
raising and relocating the ball end mill are repeated until the end
mill has traversed the entire circumference of the circumferential
intersection. In preferred embodiments, the machining step may vary
the thickness of the transition region from the first thickness to
a second thickness. The ball end mill may traverse the transition
region along a variable path, which may be a straight line, a
curved line, or any other suitable path.
According to another embodiment of present invention, a golf club
head including a face plate arranged for impacting a golf ball may
be formed. The face plate preferably varies in thickness and
includes a central thickened region surrounded by a transition
region tapering from the central thickened region to a thinner
peripheral region, and a circumferential intersection between the
central thickened region and the transition region. The inner
surface of the face plate preferably includes a plurality of tool
channels formed therein, the plurality of tool channels extending
radially outward from the circumferential intersection to an outer
edge of the peripheral region.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a partially cut-away front view of a golf club head
having a machined face plate manufactured according to the present
invention;
FIG. 2 is a rear cross-sectional view of the golf club head of FIG.
1;
FIG. 3 is a cross-sectional view of the golf club head taken along
lines 3-3 in FIG. 2 showing the machined face plate;
FIG. 4 is a cross-sectional view of the golf club head of taken
along line 4-4 in FIG. 2 showing the machined face plate, and FIG.
4A is a cross-sectional view similar to FIG. 4 showing a blank face
plate prior to machining;
FIG. 5 is a another rear cross-sectional view of the golf club head
of FIG. 1; and
FIG. 6 illustrates the use of a milling machine in a preferred
method of the present invention.
DESCRIPTION OF THE INVENTION
Referring to FIG. 1, a golf club 10 includes a head 12, a hosel 14
and a shaft 16. Head 12 includes a hollow body 18 made of a metal
material such as titanium. Hollow body 18 is formed as a shell 20,
which may be assembled from a series of forged pieces but, in the
illustrative embodiment, comprises a titanium investment casting. A
face plate 22 is attached by conventional means such as plasma or
electron beam welding to a corresponding opening 23 (FIG. 2) in
shell 20 to form hollow body 18. Face plate 22 may be a
conventional forged blank but, in the illustrative embodiment,
comprises a rolled sheet titanium blank that is machined prior to
welding to shell 20 as described more fully hereinafter.
As noted hereinbefore, because a golfer's swing tends to vary more
in the heel-toe direction than it does up or down, the inventor of
the present invention determined that the most efficient
reinforcement would be a thickened region that is preferably
elliptical and oriented so that the major axis of the reinforced
region was substantially horizontal when the club head is held in
its normal position for addressing the ball. Accordingly, face
plate 22 includes a central thickened region 24 that is preferably
elliptical in shape with its major axis 26 oriented horizontal when
the club is held in its normal address position. In the
illustrative embodiment, central thickened region 24 is between
0.130 and 0.180 inches in thickness. Central thickened region 24 is
surrounded by a transition region 28 that tapers from the central
thickened region 24 to a peripheral region 30, which in the
illustrative embodiment is 0.080 to 0.120 inches thick. Transition
region 28 is also preferably elliptical, however, for reasons that
are explained more fully hereinafter, the major axis and minor axis
of transition region 28 are a fixed amount larger than the
respective major and minor axis of central thickened region 24.
Accordingly, the aspect ratio of transition region 28 is lower than
the aspect ratio of central thickened region 24 (in other words,
transition region 28 is a "fatter" ellipse than central thickened
region 24).
With reference to FIGS. 2-6, prior to assembly of face plate 22 to
shell 20, the rear contours of the inner surface of face plate 20
are formed by a machining operation shown schematically in FIG. 6.
The process begins with a blank face plate 32 shown in FIG. 4A,
which in the illustrative embodiment comprises a blank stamped from
a rolled sheet of titanium alloy. The blank face plate 32 has a
thickness equal to the final thickness of the central thickened
region 24 of the finished face plate 22, which as noted
hereinbefore is from 0.130 to 0.180 inches in thickness. The rear
or inner surface 33 of blank face plate 32 is machined by using a
ball end mill 34 to remove a portion thereof. A revolving ball end
mill 34 is located normal to the rear surface 33 of the blank face
plate 32 at an initial location on a first circumferential
intersection 36 between the outer edge of the thickened region 24
and the transition region 28. As can be seen from FIG. 6, as the
lower cutting surface 38 of the ball end mill 34 is brought into
contact with rear surface 33 of blank face plate 32, the lower
cutting surface 38 begins to cut into rear surface 33 of the blank
face plate 32. A tool channel 40 having a width equivalent to the
width of the lower cutting surface 38 of the ball end mill 34 is
machined into the inner rear surface 33 of the blank face plate 32
by moving the revolving ball end mill 34 in a radial direction
outwardly toward and through the transition region 28 and the
peripheral region 30. As the ball end mill 34 traverses the
transition region 28, the lower cutting surface 38 is gradually
moved closer to the rear surface 33 of the blank face plate 32 to
thereby vary the thickness of the transition region 28 in the tool
channel 40. Preferably, upon reaching a second circumferential
intersection 42, located at the intersection of the transition
region 28 and the peripheral region 30, the ball end mill 34 does
not increase its depth of penetration into the blank face plate 32,
thus forming the peripheral region 30 having a constant thickness.
The ball end mill 34 may traverse the transition region 28 along
various paths including a straight or curved path. Upon reaching
the peripheral region 30, the revolving ball end mill 34 is raised
in a direction normal to the rear surface 33 of the face plate 32
and moved to a location on the outer edge of the thickened region
24 adjacent to the previous tool channel 40. The process of
machining a tool channel 40, raising the ball end mill 34, and
relocating the revolving ball end mill 34 to a subsequent location
on the elliptical outer edge of the thickened region 24 adjacent to
the previous tool channel 40 is repeated until the entire face
plate 22 is formed. The movement of the ball end mill 34 during
formation of the face plate 22 may be computer controlled. In a
preferred embodiment, the process of forming the face plate 22
results in about 95% of the surface area of the rear surface 33 of
the blank face plate 32 being machined, with about 25% of the
volume of the blank face plate 32 removed.
With particular reference to FIGS. 2-4, the major axis 26 of
central thickened region 24 is from 0.65 to 1.05 inches in length.
The minor axis 48 of central thickened region 24 is 0.25 to 0.45
inches in length. Accordingly, the aspect ratio of central
thickened region 24 is between 1.4 and 4.2. In the illustrative
embodiment, major axis 26 is approximately 0.85 inches and minor
axis 48 is approximately 0.35 inches yielding an aspect ratio of
approximately 2.4.
Major axis 50 and minor axis 52 of transition region 28 are a fixed
amount ".delta." greater than the respective major and minor axes
of central thickened region 24. In the illustrative example, the
major axis 50 and minor axis 52 are approximately 0.86 inches
greater than the respective major and minor axes of central
thickened region 24. Thus, major axis 50 in the illustrative
embodiment is approximately 1.71 inches in length and minor axis 52
of transition region 28 is approximately 1.21 inches in length.
Thus, the aspect ratio of transition region 28 is approximately 1.4
as opposed to the 2.4 aspect ratio of central thickened region 24.
The high aspect ratio central raised portion surrounded by the
lower aspect ratio transition region provides optimum distribution
of material for improved performance and reliability.
The use of a ball end mill to surface machine the inner surface of
the face plate by creating tool channels in a radial direction
improves the fatigue strength and promotes better face durability
because the tool channels are perpendicular to the direction that a
fatigue crack generally forms. Although certain illustrative
embodiments and methods have been disclosed herein, it will be
apparent from the foregoing disclosure to those skilled in the art
that variations and modifications of such embodiments and methods
may be made without departing from the spirit and scope of the
invention. Accordingly, it is intended that the invention should be
limited only to extent required by the appended claims and the
rules and principals of applicable law.
* * * * *
References